Compression connector



-May 30, 1967 c. G. ZEMELS 8 I 3,322,888

COMPRESS ION CONNECTOR Filed May 12, 1966 INVENTOR. CARL G. ZEMELS ATTORNEY 2 Sheets-Shet 1 May 30, 1967 c. G.YZEMELS I 3,322,888

COMPRESS ION CONNECTOR Filed May 12, 1966 2 Shets-Sheet 2 INVENTOR. CARLG. ZEMELS AT TORNEY United States Patent 3,322,888 COMPRESSION CONNECTORCarl G. Zemels, St. Louis, Mo., assignor to Kearney-National Inc., St.Louis, Mo., a corporation of Delaware Filed May 12, 1966, Ser. No.549,667 9 Claims. (Cl. 174-94) This application is acontinuation-in-part of my copending application Ser.-No. 378,919, filedJune 29, 1964, now abandoned.

This inventionrelates to compression fittings used on electric overheadconductors for making a connection between a line conductor and a tap,and particularly to such fittings which are adapted to accommodate arange of conductor sizes.

Compression type connector fittings of the general type referred to aredisclosed in the patent to Hoffman et al., 2,707,775, and are commonlytermed H-frame connectors, and are made of ductile metal such as deadsoft aluminum (i.e., no harder than about Rockwell H 25) or Electrolytictough pitch-copper (99.9% pure) having a hardness no greater than aboutRockwell F 45. Such fittings have a generally oval cross-sectional shapewith two conductor receiving sockets located, respectively, at theopposite ends of the major axis of the oval. At least one, and usuallyboth, of the sockets is U-shaped, and opens outwardly for readyreception of a conductor in- Y serted radially. The U-shaped socketshave a curved bottom wall, and relatively parallel side walls spacedsufficiently to easily receive a conductor of the maximum diameterintended to be used in that particular socket. Usually, one of thesockets is larger than the other-the larger one for accommodation of theline conductor, and the smaller one for the tap conductor (which isseldom as large as the line conductor).

In practice, a connector is placed on a line conductor intermediate itslength, with the larger socket astride the line conductor, and thesmaller socket astride the tap conductor. The conductors are caged inthe respective sockets by a suitable means, such as bendable memberswhich may be bent over the open mouth of each socket. A compression toolwith opposite relatively movable jaws is used to compressthe metal ofthe fitting onto each conductor simultaneously. This tool is operatedeither manually or from a suitable power source, and carries a pair ofreversely oriented, but usually identical, die pieces, one in each of apair of movable jaws. In the common hydraulically powered tool, therespective die pieces are forced toward each other in parallel (andcol-' liding) paths, while in the common manually powered tool, the diepieces are forced toward each other on arcuate (and colliding) pathswhich, during the compression stage, depart from parallel but slightly.The tool is placed on the fitting so that the respective die piecesembrace opposite sockets of the connector (and encaged conductors). Thedie pieces are then forcibly brought together to compress the fittingabout the conductors, and into conformity with the composite internalcontour of the die pieces when they have reached the limit of theirmovement toward each other. When the tool is manually operated, there isa practical limit to the force for operating the handles. It may takeseveral separate applications of the manual tool at different positionsalong the fitting to complete the compression operation, but at eachapplication, the increment of fitting embraced by the die pieces isconformed to an exterior profile corresponding with the compositeinternal contour of the die pieces when they have reached the limit oftheir movement.

The compression fitting is usually made of a ductile metal (aluminum orcopper alloy), which metal will flow under the pressuredeveloped betweenthe die pieces so as to conform the sockets with the outside shape ofthe conductors in the sockets when the dies are fully closed, i.e., whennearly brought into abutment with each other. The die compressionchanges the shape of the fitting, and during this change in shape, themetal, in excess of that necessary to fill the die cavity (at the limitof the compression stroke), flows into the sockets and elsewhere.Bearing in mind that, for practical purposes, each connector socket mustbe adapted to accommodate conductors whose outside diameters vary a fewpercent, it will be understood that the amount of socket lip metal whichmust be moved into a socket by the die compression depends upon the sizeof the conductor in that socket at the time of compression. With a givenfitting, smaller conductors require the movement of more lip metal intothe socket than do larger conductors, in order to obtain good mechanicaland electric characteristics; and larger conductors require the movementof more metal than do smaller conductors, but the excess must gosomewhere other than into the socketif, as is desirable, particularlywith manually powered tools, the dies be closed to the limit of theirmovement, regardless whether the conductors in the sockets are atmaximum or at minimum size. Otherwise, with a manually operated tool,there is no assurance that the requisite compression has been applied.

Now it can be readily appreciated that if the'conductor is smaller indiameter than the socket is intended to accommodate, it is likely thatsuch under-size conductor will not be gripped tightly when the fittingis compressed. With such an under-size conductor, in order to produceenough metal flow in the fitting to force the metal completely aroundthe conductor, either the die cavities have to be smaller to produce agreater reduction and a greater metal flow, or the socket in thecompression fitting has to be made smaller so that less metal isrequired to flow into surrounding relation with the conductor whichrequires that smaller'die pieces be used. If the die is made smaller,then, of course, this die would be unsuitable for use on the fittingwhen a larger conductor is in the socket. On the other hand, it isimpractical to require the use of more than one size die on a given sizeconnector,

and if the cavity in a given die is large enough to close about itscorresponding connector with the maximum intended size conductor in itssocket, it may not move enough metal into the socket when occupied bythe minimum intended size conductor. Thus, there has been a rathernarrow limit to the range of conductor sizes which H-frame compressiontype fitting for use in connecting conductors in electric lineinstallations, which fitting may be compressed, without requiringunreasonable effort, to the final contour of the same die set about anyof a rela tively wide range of sizes of conductors.

In previous efforts to increase the conductor accommodation range ofH-frame connectors, the wrap-around of the socket lips about theconductors in the socketsparticularly the smaller sockethas been erraticunless removable parts were resorted to. Hence, it is a further objectof theinvention to assure adequate wrap-around of both conductors duringthe stages of compression (at a given cross-section) prior to themovement (at that cross-section) of a substantial part of the connectormetal elsewhere than into the sockets. 7

Generally stated, the invention achieves both of the aforesaidobjectives by the provision of a void in the body of metal whichintervenes opposite conductor receiving sockets; and regulating thelocation and magnitude of V such void to control and accommodate themovement of connector metal sequentially during the compressionoperation, so that wrap-around of the conductors by the lips of bothsockets is assured before cold-flow occurs, to any appreciable extent,between other increments of the connector cross-section undercompression. The contemplated location of the void within saidintervening body of metal is essentially such as to create a greaterconstriction in the connector metal at the root ends of their thickersocket lips than at the root ends of their thinner socket lips-it beingunderstood that to maintain uniformity of profile about the socket lips,the larger socket customarily has thicker lips than does the smallersocket. For connector fittings of conventional design, the location ofthe void, in accordance with the present invention, may be more simplyexpressed as: d is less than d, where d is the shortest distance betweenthe void and the smooth interior wall of the smaller socket; and d isthe shortest distance between the void and the smooth interior wall ofthe larger socket.

The void contemplated by the present invention may be either on theinside or the outside of the body of metal which intervenes the oppositeconductor receiving sockets, and can be formed during the process ofextruding the stock from which the individual fittings are subsequentlyto be cut. Whether the void is in the form of opposite externalindentations or in the form of one or more internal holes, it preferablyextends from end to end of the fitting substantially parallel to theaxes of the respective conductor receiving sockets, but substantiallyspaced from the concave surfaces of the sockets which are ultimately tobe contiguous with conductors. Such voids provide a major constrictionin the body of metal which intervenes the socket-s, and such majorconstriction delineates two pairs of minor constrictions located,respectively, between the body of the metal which intervenes the socketsand the several bodies of metal which constitute socket lips.

The magnitude of the void, or voids, which produce the aforesaid majorconstriction does not affect the function or operation of theconstrictions, save to the extent that finite dimensions of the voiddetermine the termini (at one end) of the constrictions, but themagnitude of the voids must be maintained sufficiently low that a voiddoes not defeat the purpose of adjacent minor constrictions bypermitting cold-flow of metal from socket lips before metal from thesame socket lips has wrapped around the conductors in the sockets. Onthe other hand, it will be understood that when each conductor receivingsocket of a given connector is being occupied by conductors of themaximum size which they will accommodate respectively, the maximumamount of metal is required to be moved by cold-flow from the socketlips to other portions of the connector. A substantial amount of thiscold-flow will take place endwise of the connector, but the balance ofit must be accommodated by the aforementioned voids if, as is desired,the ultimate profile to which a connector is compressed is the same whenoccupied by conductors at either end of its size range of accommodation.For example, the cross-sectional area of the void (e.g., the sum of thecross-sectional area of two exterior indentations) is preferably betweenand 35% of (AA'+BB), where A and A are, respectively, thecross-sectional areas of the maximum and minimum size conductors usablein one socket, and B and B' are, respectively, the cross-sectional areasof the maximum and minimum size conductors usable in the other socket.Substantially the same finite cross-sectional area of the void can bearrived at, without specifically involving conductor size range, if itbe assumed that the connector is designed to accommodate, in eachsocket, conductors whose diameter is as small as about 60% of the socketdiameter. Given that assumption, and the additional assumption that theinterior surface of neither socket is undulated, the preferredcross-sectional magnitude of the void is the sum of the cross-sectionalareas of two exterior indentations or side channels, and may be arrivedat by using the following equations for calculating the cross-sectionalarea (bXh) of each side channel:

h'=.025:15%C/b b=.150i15% (W) where C is the cross-sectional area of theconnector including the side channel areas (but not including the socketareas), said cross-section being normal to the axes of the sockets;where W is the width (i.e., the dimension perpendicular to a planeincluding the axes of both sockets); where b is the average depth (i.e.,in the dimension parallel to W) of a side channel; and where h is theaverage height (i.e., in the dimension perpendicular to b in the planeof the cross-section) of a side channel.

More empirically, when the connector is of the general design shown inthe accompanying drawing, and it is desired to accommodate conductorswhich vary in outside diameter from 100% (minus clearance) of the socketwidth to about 60% thereof, the cross-sectional area of the void can bedetermined, for practical purposes, as between about 4% and about 12% ofthe sum of socket areas, the percentage being toward the upper limit asthe difference between the respective socket areas becomes greater, andas the difference between the maximum and minimum size conductors to beaccommodated in a socket becomes greater.

The embodiment of the invention hereinafter described has the usualH-frame construction with conductor receiving sockets at opposite endsof the major diameter, and is provided, at the crossbar area, with voidsin the form of exterior channels whose combined cross-sectionapproximates twice the product of b times it aforesaid. These channelsare preferably so designed and located in the body of the fitting as toresist compression by the dies until after the conductor receivingsockets have completely closed about the respective conductors. Anysubsequent further movement of the dies to completely close, then closesthe side channels to the degree necessary to compensate for size (aboveminimum) of the conductors in the respective sockets. When the channels,or other form of void, are located in the crossbar zone between thebottoms of the sockets, then the spacing of the conductor receivingsockets will be decreased, during compression of the channels, in adegree determined by the size of the conductors above minimum within therange for which the connector is intended.

Other objects and advantages of this invention will ap-* pear from thefollowing detailed description which is in such full, clear and conciseterms as to enable any person skilled in the art to make and use thesame when taken in conjunction with the accompanying drawings, forming apart thereof, and in which:

FIGURE 1 is a view in perspective showing one end and one side of acompression type electric fitting constructed in accordance with thisinvention;

FIGURE 2 is an end view in full lines of the fitting shown in FIGURE 1,with broken lines indicating a fitting of the same size which is ofstandard configuration for comparison purposes;

FIGURE 3 is a view similar to FIGURE 1 illustrating the relativeposition of the parts of the fitting when applied to conductors ofminimum size in the range of diameters to which the fitting isapplicable;

FIGURE 4 is a view of the fitting shown in FIGURE 3 after beingcompressed by full closing of the dies;

FIGURE 5 is a view similar to FIGURE 1 illustrating the relativeposition of the parts when the fitting is ap-- plied to conductors oflarger size in the range of diameters to which the fitting isapplicable; and

FIGURE 6 is an end view of the fitting shown in FIG- URE 5 after beingcompressed by closing the dies of the same size as shown in FIGURE 4.

' body 1 is extruded with oppositely opening conductor receiving sockets2 and 3 formed between opposed lips. with the width of the dajacentsocket. The lips 6 and 8 These sockets are usually of difierent widthand depth to accommodate a different size range of conductor diameters,and the thickness of the lips-varies inversely with the width of theadjacent socket. The lines 6 and 8 carry bendable tabs 11 and 12,respectively. The fitting is constructed externally so as to begenerally rounded,

but preferably not of exactly the same contour as the dies with which itis to be used, on the lips 5 and 6, as well as 7 and 8. Between the lips5 and 7, and 6 and 8, the external sides. of the body 1 are generallyflat and have the channels 14 and 16 formed therein. Only one pair ofchannels is shown, but it should be understood that several narrowchannelsare regarded as the equivalent of one wide channel.

FIGURE 2 shows, in full lines, the outline of a fitting, such as that inFIGURE 1, and, in dotted lines, a standard fitting of comparable size.The difference intended to be emphasized here is not only the presenceof outside channels 14 and 16, but also the difference indepth of thesockets 2 and 3 as compared with those of a standard fitting of the samesize. It will be readily apparent that, absent the channels 14 and 16,there is more metal in the body 1 shown in full lines than in the bodyoutlined by broken lines. Comparison. also will reveal that the openchannels 14 and 16 reduce'the amount of metal in the body 1 so that itis roughly comparable to the amount of metal in a standard fitting ofthe same size.

The socket area herein referred to ,is the C-shaped space embraced bythe lips 5 and 6 for socket 2, and embraced by lips 7 and 8 for socket3. The outward extremity of each socket area is a straight line tangentwith the tip of lip 5 or 7 and parallel with dimension W.

FIGURE 2 alsoshows the location of dimensions hereinbefore designated b,h and W, as well as indicating that the shortest distance d from achannel 14 or 16, to the bottom of a socket 2 is greater than theshortest distances at from either channel to the smaller socket 3.FIGURE 2 also identifies the dimensions D D and't, which are involved inarriving at the optimum finite ratios of d'/d according to the equation:

d D t X t (W-t KW) where K is a coefiicient having a value of '0.33($0.05).

It should be understood that the usual compression dies used on fittingsof this type have put cylindrical cavities of constant radius. Thesedies are usually used in the jaws of a hand operated tool which isconstructed with stops to limit closing so that the dies do not comeinto contact with each other at fully closed position.

Since a fitting of standard size has a certain amount of metal, it willbe obvious that to fullyfclose the dies on fittings by a manual operatedtool using the same size dies will require more eifort as the size ofthe conductors in the sockets is increased. Conversely, full closing ofthe dies will produce less total flow in the metal of the fitting as thesize of the conductors in the sockets is decreased, because more of thesocket lip metal comes to rest as wrap-around of the conductor in thesocket than the same socket can accommodate when it is 00- cupied by asubstantially larger conductor.

Smaller conductors require the movement of more metal into the socketthan do larger conductors, in order to obtain good mechanical andelectric characteristics. These conflicting requirements haveeffectively blocked full realization" of versatility in the respectsmentioned. As illustrated in the succeeding views of the drawings,however, a fitting based upon the concept here disclosed meets all ofthe requirments, and, at the same time, extends the size range ofconductor diameters accommodated by the fitting without using a varietyof dilferent sized dies.

In FIGURE 3, a fitting is shown applied to conductors I of the'minimumintended diameter. The diameters of the conductors 19 and 20 are muchsmaller than the width of the sockets 2 and 3, respectively. Tabs 11 and12 are next bent over by finger pressure to hold the conductors 19 and20 in place. Thereafter, the fitting 1 is compressed in a pair of dies22 and 24 with cavities of constant radius, as above described. Duringthe compression, lips 5 and 6, 7 and 8, fold inwardly, and there is aflow of metal due to the fact that the dies fill during closing. Thisflow of metal causes the metal of the fitting to enter between wires ofthe conductors 19 and 20 to form the desired joint or connection betweenconductors. It will be observed that there is sufficient metal to fillthe dies 22 and 24, and that no appreciable contraction of channels 14and 16 has taken place.

In FIGURE 5, the same size fitting as in FIGURE 3 is shown applied toconductors in the maximum intended diameter. In other words, conductors26 and 28 have a diameter corresponding to socket width, and, of course,conductors 26 and 28, because of their larger diameter, have much moremetal than conductors 19 and 20. After tabs 11 and 12 are pushed in byfinger pressure to hold the conductors 26 and 28, then the compressiontool is applied, and the fitting 1 compressed by fully closing the samedies 22 and 24. During this operation, lips 5, 6, 7 and 8 are wrappedaround the conductorsthe wrap-around of lips 5 and 6 proceeding fasterthan the wrap-around of lips 7 and 8. After the wrap-around phase of theoperation is completed, or substantially so, further die pressure causesthe metal of the fitting to flow into and between the exterior strandsof conductors '26 and 28, and also-because conductors 26 and 28 are ator near the maximum within the size range accommodatable by theconnector-causes flow from the lips into the strut-like crossbar of body1 between channels 14 and 16, and when the dies are fully closed,channels 14 and 16 have closed almost fully as shown in FIGURE 6.

This decreases the spacing betweencond'uctors 26 and 28. Thus, as thesize of the conductors increases from the minimum toward the maximumwithin the accom- ,modatable size range,-channels 14 and 16 are closedincreasing amounts, but, at each cross-section under compression, theflow of metal is sequential first to wrap the lips around theconductors, and then otherwise, e.g., from the lips toward the socketintervening crossbar, from the latter into the side channels, andendwise out of the increments undergoing compression.

The relationshipof d d tends to restrain the flow of metal from the lipsinto the socket intervening crossbar until after the lipsof both socketshave wrapped around their respective conductors. Otherwise, once thethinlips (about the larger socket) have wrapped about their conductor,the void (formed, for example, by the side channels) is likely tocollapse before the thick lips (about the smaller socket) havesufiiciently wrapped around their conductor to assure an efficientconnection. It is the location rather than the finite magnitude of thevoid which so controls the sequence of metal flow.

On the other hand, the finite magnitude of the void controls thefacility with which the connectorscan be compressed to the limit oftheir appropriate die set without regard to whether the encagedconductors are at one extreme or the other of the range of sizesaccommodatable by the connector.

An illustrative example of the finite dimensions of the various parts ofa typical connector made in accordance with the present invention is asfollows:

7 D inches 0.58 D do 0.39 t do 0.40 W do 0.885 d do 0.255 d do 0.35 b do0.14 h do 0.11 C square inches 0.705

Such a connector is eificiently usable with line conductor in socket 2varying from an outside diameter of 0.461 inch up to within a fewthousandths (clearance) of 0.5 8 inch; and with tap conductor in socket3 varying from an outside diameter of 0.25 inch up to within a fewthousandths (clearance) of 0.39 inch.

The improvement in size versatility or range of conductor sizes obtainedby redistribution of metal in a fitting as above described is not theonly advantage of this invention. For instance, the fitting would havelittle sales appeal or utility if the die pressure needed exceeded thestrength of the lineman operating the manual tool. In this respect, thisinvention also exceeds expectations because comparative tests have shownthat a standard H- frame connector (Kearney 348-81) requires over eightypounds of manual force on the tool handles in order to fully close thedies during each tool application to the fitting with a 4/0 ACSRconductor in one socket, and 1/0 str. compressed conductor in the other.These are the largest conductor sizes for the fitting which is shownoutlined in broken lines in FIGURE 2. Tests on the fitting shown in fulllines have shown that during each tool application to the fitting withthe same size conductors, the manual force on the tool handles requirednever exceeded seventy pounds. In fact, the force required for the firststroke of the tool was about sixty-eight pounds, and thereafter itdecreased for subsequent strokes to about fifty-one pounds.

Changes in and modifications of the constructions described may be madewithout departing from the spirit of my invention, or sacrificing itsadvantages.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. In a compression connector of the character described havingoppositely disposed conductor-receiving sockets, one of said socketsbeing of larger cross-sec 'tional dimension than the other, and a bodyof ductile metal extending crosswise of said connector between saidsockets, the improvement which comprises, said crosswise extending bodyof metal having a void therein for accommodating compression of saidbody to shorten the distance between said sockets, said void beinglocated in spaced relation with both sockets and substantially closer tothe smaller socket than to the larger socket.

2. The connector of claim 1 wherein the cross-sectional area of the voidis between 0.034 and 0.046 of the crosssectional area of the connectorincluding the void but excluding the socket space.

3. The connector of claim 1 wherein the void delineates constrictions insaid crosswise extending body, said constrictions extending from saidvoid to each of said sockets, and the constrictions extending to thelarger socket are of greater length than the constrictions extending tothe smaller socket.

4. In a compression connector of the character described havingoppositely disposed conductor receiving sockets, each of said socketsbeing proportioned to re ceive conductors Whose outside diameters varybetween a maximum and a minimum, and a body of ductile metal extendingcrosswise of said connector between said sockets, the improvement whichcomprises: said body having a void substantially spaced from saidsockets and extending for the full length of said body, and said voidhaving a cross-sectional area of between 0.034 and 0.046 times thecross-sectional area of the connector including the void but excludingthe socket space.

5. The improvement of claim 4 wherein said void is open to the exteriorof said connector.

6. The improvement of claim 4 wherein said void is delineated bychannels on the exterior of said body at opposite sides of theconnector.

7. The connector of claim 6 wherein the average dimension h of saidchannels in the direction parallel to a plane including the axes of bothsockets is 0.0200i15% (C/B) and the average dimension b thereof in thedirection perpendicular to said plane is where W is the dimension of theconnector parallel to b and C is the cross-sectional area of theconnector including the channels but excluding the socket space.

8. The connector of claim 7 wherein the shortest distance d between eachchannel and the smaller socket is related to the shortest distance dbetween each channel and the larger socket according to the formula:

D D D KW D -D t d D t X t (V -t KW where K is a coefiicient having avalue of 0.33:0.05, where t-is the distance between the bottoms ofopposite sockets, where D and D are the widths of the larger and smallersockets respectively, and where the other values are as indicated inclaim 7.

9. An H-frame compression connector having opposite sockets for thereception respectively of line conductors and tap conductors, saidsockets having smooth concave bottom surfaces intervened by a crossbarof metal, said crossbar having indentations at the opposite sides ofsaid crossbar, said indentations extending lengthwise of the connectorand each having a cross-sectional area of between 4% and 12% of the sumof the cross-sectional areas of the sockets, whereby said connector iscompressible to the same ultimate cross-section, in the same compressiondies, about conductors whose outside diameters vary between (minusclearance) and 60% of the width of said sockets.

References Cited UNITED STATES PATENTS 11/ 1964 Toedtrnan l7494 5/1965Lynch et al l7494 X

1. IN A COMPRESSION CONNECTOR OF THE CHARACTER DESCRIBED HAVINGOPPOSITELY DISPOSED CONDUCTOR-RECEIVING SOCKETS, ONE OF SAID SOCKETSBEING OF LARGER CROSS-SECTIONAL DIMENSION THAN THE OTHER, AND A BODY OFDUCTILE METAL EXTENDING CROSSWISE OF SAID CONNECTOR BETWEEN SAIDSOCKETS, THE IMPROVEMENT WHICH COMPRISES, SAID CROSSWISE EXTENDING BODYOF METAL HAVING A VOID THEREIN FOR AC-